Unless your heart is racing or otherwise acting up, you probably don’t often think about how this all-important organ functions. As you read this, your heart is performing an incredible balancing act that’s crucial to keeping you alive and healthy.

“The heart beats because of electricity,” Shephal Doshi, M.D., director of cardiac electrophysiology at Providence Saint John’s Health Center in Santa Monica, California, tells SELF. No, not the type that keeps your lights on, although that would be interesting. These are electrical impulses from a group of cells in your heart’s right atrium (chamber) that act like your own internal pacemaker. These cells, known as your sinoatrial (SA) node, tell your heart when and how to beat in order to send oxygen-rich blood throughout your body.

At rest, it’s normal for your heart to respond to these signals by beating anywhere from 60 to 100 times per minute. Anything higher than that is known as tachycardia, the fancy way of describing the sensation that your heart is galloping a mile a minute. When your heart starts pounding, your first thought might be, OMG, this is it, I’m having a heart attack. But a heart attack is most likely to cause symptoms like pain in your jaw, neck, back, arms, or shoulders, discomfort or pain in your chest, shortness of breath, fatigue, nausea, and vomiting. If your heartbeat feels out of control, a heart attack probably isn’t to blame. Instead, here are 10 possible reasons why your heart is racing.

1. You’re stressed.

When you encounter something stressful, your sympathetic nervous system and adrenal glands release a surge of norepinephrine, also known as adrenaline, Camille Frazier-Mills, M.D., a cardiologist at Duke Electrophysiology Clinic, tells SELF. Receptors in your heart respond to these triggers and can make your heart rate pick up. If you can’t immediately solve whatever’s making you stressed, try deep breathing to at least help you feel better in the moment. The Mayo Clinic suggests taking deep breaths in through your nose so that you feel your stomach rise, not your chest, and exhaling through your nose as well. Focus on your breath and the rise and fall of your abdomen throughout.

2. You’re beyond wired on caffeine.

While most people can handle a certain level of caffeine just fine, overdoing it can make your heart speed up. “Caffeine is a stimulant that can cause the release of adrenaline and make your heart beat faster,” Dr. Doshi says.

According to the Mayo Clinic, it’s safe for adults to have up to 400 milligrams of caffeine a day, or around the amount in four cups of coffee, 10 cans of soda, or two energy drinks (caffeine content varies based on the specific beverage).

“A bunch of patients come to see me with an elevated heart rate, then they tell me they drink multiple highly caffeinated beverages daily,” Dr. Mills-Frazier says. “They’re revving themselves up.” This is most likely to happen if you’ve had too much caffeine, but it could also happen in response to small amounts if you’re just sensitive to this stimulant. Try cutting back on caffeine gradually to see if it reduces your racing heart. If not, get in touch with your doctor.

3. You have a cold or fever.

If your pounding heart is accompanied by typical signs of a cold or fever, like an elevated temperature, coughing, and sneezing, this is likely the culprit. Battling an infection requires your body to work harder than usual, and that includes making your heart beat faster in order to fight for homeostasis (its usual stable condition) and kick the infection to the curb, Dr. Mills-Frazier says.

4. You’re not getting enough sleep.

When you sleep, your body isn’t doing as much, so your heart can slow down. “Sleep is your time to reset. If you’re not getting that recovery phase, your adrenaline levels during the day can be higher,” Dr. Mills-Frazier says. Excess adrenaline charging through your system during the day can lead to a faster heartbeat. The National Sleep Foundation recommends adults get seven to nine hours of sleep per night. If you have trouble clocking those restful minutes, check out some tips for beating insomnia.

5. You’re on some kind of medication that affects your heart.

There are tons of them out there. “Whether it’s related to osteoporosis, allergies, ADHD, or another condition, a lot of medications will increase circulating adrenaline and cause someone to feel like their heart is racing,” Dr. Doshi says. This happens so often that doctors will often first ask which medications you’re taking when you tell them your heart is beating too quickly. Depending on your medication and medical history, a racing heart can be expected or a sign that you might need to try a different option. Only a doctor can tell you for sure.

6. You’re pregnant.

Pregnancy is one heck of a roller coaster for your body, including your heart. In order to support the growing pregnancy, your blood volume goes up, and your heart has to work harder to pump out that extra blood, leading to a higher heart rate, Dr. Doshi says. This is completely normal, but if you’re concerned, check in with your ob/gyn just to make sure.

7. You’re having a panic attack.

Around 2 to 3 percent of Americans experience an episode of panic disorder in any given year (otherwise known as a panic attack), according to the American Academy of Anxiety and Depression. Panic attacks are characterized by sudden, unexpected, often paralyzing bouts of fear. A rapid heartbeat is a common symptom, and it can terrify people even more. “You start releasing more adrenaline, and it becomes this vicious cycle,” Dr. Mills-Frazier says, adding that sometimes it’s difficult to tease out whether a rapid heartbeat contributes to someone having a panic attack or vice versa. If you think you’re having panic attacks, don’t suffer in silence. Talk to your doctor or therapist to figure out which treatment option can best help you avoid these awful episodes.

8. Your thyroid is in overdrive.

Your thyroid gland produces various hormones, like thyroxine and triiodothyronine, which affect a ton of your body’s systems, according to the Mayo Clinic. If you have hyperthyroidism, your thyroid is overactive and produces too much thyroxine, which in turn speeds up your body’s metabolism too much. This can result in a rapid or irregular heartbeat, along with symptoms like an increased appetite and sudden weight loss. There are plenty of medications out there to treat hyperthyroidism, including beta blockers to specifically address your quick heart rate.

9. You have anemia.

Anemia happens when your blood doesn’t provide enough oxygen throughout your body, according to the National Heart, Lung, and Blood Institute. This can occur if you don’t have enough red blood cells, or if you don’t have enough hemoglobin, the iron-rich protein that carries oxygen from your lungs to other parts of your body. In either instance, your heart has to work harder to get blood to every part of you, so you can experience a faster heart rate, Dr. Doshi says. This won’t be your only sign of anemia, though. If you have this blood disorder, you can also expect to feel things like fatigue, dizziness, headache, and pale skin.

10. You have a heart arrhythmia.

A heart arrhythmia happens when there’s some sort of electrical malfunction in your heart, which can cause it to beat irregularly. There are many forms, and they have different causes, but they can often make it feel like your heart is beating quickly or strangely out of nowhere. Although an arrhythmia sounds like a dire diagnosis from Grey’s Anatomy, they actually aren’t always serious. “Many arrhythmias are not life-threatening,” Dr. Mills-Frazier says. “Obviously with higher-risk patients, they can be, but they’re often treatable.” Arrhythmias often present with side effects like dizziness, nausea, fainting, chest pain, and shortness of breath, according to the American Heart Association.

Ultimately, there are lots of reasons your heart may be racing.

Sometimes it’s nothing major. Other times, especially when accompanied by symptoms like feeling lightheaded or dizzy, having chest pain, or feeling fatigue, it can be a sign that you should see a doctor. “It doesn’t matter how healthy you are or how healthy you think you are,” Dr. Doshi says. “If your heart doesn’t feel right for you, it’s worth getting a checkup.”